Description
Apoptosis plays a major role in normal organism development, tissue homeostasis, and removal of damaged cells. Disruption of this process has been implicated in a variety of diseases such as cancer (reviewed in 1). Apoptosis is induced by certain cytokines including TNF and Fas ligand of the TNF family through their death domain containing receptors, TNF-R1 and Fas. Several death receptors including DR3, DR4, DR5, and DR6 have been identified. Like TNF-R1, DR6 (also known as TNFRSF21) interacts with death domain containing adapter molecule TRADD. Overexpression of DR6 induces apoptosis and activates NF-kB and JNK. DR6 is widely expressed in human tissues and cell lines (2). Recently, DR6 was found to interact with an amino-terminal fragment of the Beta-amyloid protein (APP) in neurons, activating a caspase 6-dependent apoptotic event leading to axonal degeneration and pruning (3). The doublet observed in the SDS-PAGE is likely due to incomplete removal of the signal sequence